Model ordered lists, nested settings, and typed event configuration — Change one requirement

PART I

Warm-up

Reconnect with a useful idea before starting model ordered lists, nested settings, and typed event configuration. In one or two sentences, describe the input, output or host boundary from the previous exercise that this lesson builds on. If you are arriving directly, skim the worked example first; there is no locked prerequisite.

A rough note is enough. You can revise it after the example.

PART II

Instruction & guided example

Adapt selection after filtering

An ordered collection carries order and identity as different facts. A displayed position may change when elements move; a stable record identity should continue naming the same record. Predict transformations using supplied tiny inputs before choosing a configuration or host API.

Items are [{id:2, active: true},{id:7, active: false},{id:11, active: true}]. Selected identity is11. A supplied host filter retains active rows in input order and leaves selection by identity when that id remains.

Worked reasoning: The filtered identities are2,11. Selected11 survives and now occupies position1 instead of2. Keeping the selected index2 would point beyond the two-item result.

Failed alternative: Reusing the original position after a filter confuses stable identity with a now-invalid location.

Worked reasoning and supplied artifact

Input ids:[2,7,11];selected id11 at position2
Predicate:active==true
Output ids:[2,11];selected id11 at position1
Position2:no element

Illustrative example from the proposed WillowScript design. The language and WUIX/WMATH/WDB/WAUDIO/WTMP services are not implemented in the supplied source. This site has no interpreter, VM or native host and does not execute or certify the snippet.

Try the guided change

Reconstruct the supplied worked case first: list its inputs, intermediate decisions and final artifact. Compare each row with the explanation and identify exactly where the rejected alternative fails. Then use the changed inputs in Part IV for independent work.

• Write the supplied inputs and initial state before following the example.
• Reconstruct each intermediate calculation or host decision, then compare with the worked artifact.
• Explain why the contrasting alternative fails before attempting the changed inputs in Part IV.

PART III

Take a breather

Step back after the guided example. Look away from the screen, stretch, or reread your prediction. This is an optional learning pause, not a timer or an assessment gate.

When you return, try to name the lesson’s key idea without copying its wording. If that feels difficult, return to Part II and trace one line rather than restarting the entire lesson.

PART IV

Independent practice

Project context: Reusable configuration workspace. Build a small, understandable change around model ordered lists, nested settings, and typed event configuration.

Filter ids4,8,15,19 with only8 and19 active; retain selected19. Then analyze selected15 under an explicit clear-if-removed policy.

What to produce

A filter/selection table with surviving and removed-selection cases.

• State the intended behavior in a sentence before editing.
• Use only source-backed syntax and the host services whose contract you have been given.
• Record a normal case and a boundary or unavailable-resource case.
• Label hand predictions separately from anything actually measured in a supplied toolchain.

Syntax colors are a reading aid, not a compiler. The line you are editing stays uncolored until you move to a different line; capitalization is never changed. Drafts stay on this browser and code is not executed.

import wuix.widget;
const button = widget.Button({
    text: "Continue",
    events: {
        click: fnc() -> void {
            navigator.open("dashboard");
        }
    }
});

PART V

Self-check

Use this check to notice what to revisit. It does not award a private course grade, block another page or claim to verify compiled code. Every answer has a learning explanation.

You may keep exploring even if you are unsure. Use the hint, compare the trace, and revise your explanation.

PART VI

Recap & small task

Bring the idea back to the mod feature you are building. A useful recap connects the mechanism to a decision you can make in your own code.

• Adapt selection after filtering
• Filter ids4,8,15,19 with only8 and19 active; retain selected19. Then analyze selected15 under an explicit clear-if-removed policy.
• Separate source-backed behavior, host requirements and untested predictions.

One small recap task

Resolve selected identity in the transformed collection rather than carrying an old index.

This marks your personal practice record only. It is not a certification or an official workspace assessment.